If you don't need all of the features of TurboTax Premier, you can downgrade from TurboTax Premier to Deluxe or the Federal Free version of TurboTax Online, as long as you haven't paid yet (or registered in a free version) - but please bear in mind that you will need to clear any data which you have entered, and start over in the other TurboTax version. This is the only available method to downgrade versions.
Please see the following TurboTax FAQ, "Can I switch to a lower-priced version of TurboTax Online?":
https://ttlc.intuit.com/replies/4248526